Deep below the ancient volcanoes scattered around the Philippines sits a simmering stockpile of intense heat that officials hope will help revive the nation's sputtering green energy machine.The Philippines - thanks to its spot in the Ring of Fire zone of Pacific volcanoes - has long been one of the world's top producers of geothermal power, but years of neglect have sent the industry sliding.Now a surge of new exploration efforts is underway in a nation that has some of the world&#